Paris -LRB- CNN -RRB- Six survivors of the Paris kosher supermarket siege in January are suing a French media outlet for what they call dangerous live broadcasting during the hostage-taking .

According to Paris prosecutor 's spokeswoman Agnes Thibault-Lecuivre , the lawsuit was filed March 27 and a preliminary investigation was opened by the prosecutor 's office Wednesday .

The media outlet , CNN affiliate BFMTV , is accused of endangering the lives of the hostages , who were hiding in a cold room during the attack , by broadcasting their location live during the siege .

BFM in a statement Friday said one of its journalists `` mentioned only once the presence of a woman hidden inside the Hyper Cacher , on the basis of police sources on the ground . ''

`` Immediately , the chief editor felt that this information should not be released . It therefore has subsequently never been repeated on air or posted on-screen . BFMTV regrets that the mention of this information could cause concern to the hostages , as well as their relatives , that their lives were in danger , '' the statement said .

Gunman Amedy Coulibaly , also suspected in the slaying of a police officer , stormed the Hyper Cacher Jewish supermarket on January 9 , killing four people and taking others hostage .

He was killed in the police operation to end the siege .

A 24-year-old supermarket employee , Malian-born Lassana Bathily , was hailed as a hero afterward when it emerged that he had risked his life to hide 15 customers from Coulibaly in the cold room .

The hostage-taking was the culmination of three days of terror in Paris that began with the January 7 shooting of 12 people at the offices of French satirical magazine Charlie Hebdo .

The two brothers blamed for that attack , Cherif and Said Kouachi , were killed on January 9 after a violent standoff at an industrial site .

The terror attacks claimed the lives of 17 people and put France on a heightened state of alert .

CNN 's Ariana Williams reported from Paris , and Laura Smith-Spark wrote from London . CNN 's Pierre Meilhan contributed to this report .

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Six people taken hostage in a kosher market siege say media outlet endangered their lives

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They hid in a cold room during the attack in Paris by gunman Amedy Coulibaly